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971.
Bao-Xuan Zhu 《Linear algebra and its applications》2010,433(5):928-261
In this paper, we show that among all the connected graphs with n vertices and k cut vertices, the maximal signless Laplacian spectral radius is attained uniquely at the graph Gn,k, where Gn,k is obtained from the complete graph Kn-k by attaching paths of almost equal lengths to all vertices of Kn-k. We also give a new proof of the analogous result for the spectral radius of the connected graphs with n vertices and k cut vertices (see [A. Berman, X.-D. Zhang, On the spectral radius of graphs with cut vertices, J. Combin. Theory Ser. B 83 (2001) 233-240]). Finally, we discuss the limit point of the maximal signless Laplacian spectral radius. 相似文献
972.
(001)-oriented strontium bismuth tantalate thin films have been grown on Pt/TiO2/SiO2/Si (100) substrates by pulsed laser deposition. The room-temperature current–electric field dependence of the films has been
investigated, which revealed a space-charge-limited conduction mechanism. The microstructures of grain boundaries and structural
defects in these films were also examined by transmission electron microscopy and high-resolution transmission electron microscopy,
respectively. The grains of the films deposited at 550 °C exhibited polyhedral morphologies, and the average grain size was
about 50 nm in length and 35 nm in width. At a small misorientation angle (8.2°) tilt boundary, a regular array of edge dislocations
with about 3-nm periodic distance was observed, and localized strain contrast near the dislocation cores was also observed.
The Burgers vector b of the edge dislocation was determined to be [110]. At a high misorientation angle (39.0°) tilt grain boundary lattice strain contrast associated with the distortion of
lattice planes was observed, and the mismatching lattice images occurred at about 2 nm along the boundary. The relationship
between microstructural defects at grain boundaries and leakage currents of these films is also discussed.
Received: 8 September 2000 / Accepted: 18 December 2000 / Published online: 28 February 2001 相似文献
973.
E. F. Jones P. M. Gore J. H. Hamilton A. V. Ramayya A. P. de Lima R. S. Dodder J. Kormicki J. K. Hwang C. J. Beyer X. Q. Zhang S. J. Zhu G. M. Ter-Akopian Yu. Ts. Oganessian A. V. Daniel J. O. Rasmussen I. Y. Lee J. D. Cole M. W. Drigert W.-C. Ma 《Physics of Atomic Nuclei》2001,64(7):1157-1164
The levels in 162Gd were identified in spontaneous fission studies. Its transition energies are remarkably similar to those in 160Gd. From that work, an analysis of yrast bands in even-even proton to neutron-rich Ba to Pb nuclei led to the discovery of a new phenomenon, shifted identical bands (SIB). SIBs are yrast bands in neighboring nuclei (a, b) with moments of inertia which are identical when shifted by a constant amount κ, so J 1a (1+κ)=J 1b , from 2+ to 8+ and higher to 16+. Out of over 700 comparisons, 55 SIBs were found from stable to the most neutron-rich Ce-W nuclei with $\left| {\bar k} \right|$ between 1.5% and 13%, where the spread in κ is less than ±1%, and only four identical bands ( $\bar k \cong 0$ ). As examples, we found for 158Sm-160Gd, $\bar k = \left( { - 3.2_{ - 0.2}^{ + 0.1} } \right)\%$ (where the ± is the total spread in κ from ?3.1 to ?3.4); 156Nd-160Gd, (?10.6 ?0.2 +0.4 )%; 158Sm-160Sm, (3.4 ?0.3 +0.5 )%. The J 1 values were fitted to a variable moment of inertia model with parameters J 0 and C whose values correlate with the SIB J 1 values. The SIBs are not correlated either with deformation or with the N p N n product of the IBA model. 相似文献
974.
Let F be a field with characteristic 0,V=F~n the n-dimensional vector space over F and let G be a finite pseudo-reflection group which acts on V.Let χ:G→F~* be a 1-dimensional representation of G.In this article we show that X(g)=(detg)~α(0≤α≤r-1),where g∈G and r is the order of g.In addition,we characterize the relation between the relative invariants and the invariants of the group G,and then we use Molien's Theorem of invariants to compute the Poincaré series of relative invariants. 相似文献
975.
976.
根据量子统计模型 (QSM )的计算分析 ,找到了一个提取核反应过程中熵产生的新的可观测量 .核反应过程中约化d的产额d/ (d t 3 He 4 He)和熵有单调的函数关系 ,并且和体系的碎裂密度 (ρ/ ρ0 )及体系的N/Z都无关 ,可以作为提取核反应过程中熵产生的一个观测量 .和目前已经有的其他方法相比 ,约化d产额这一提取熵方法可以用于较低能量的重离子核反应中 ,并且数据处理分析简单 .对于 35MeV/u4 0 Ar 197Au的核反应过程所提取的熵和利用约化带电粒子多重性提取的熵结果一致 .结合后角类靶热核发射体系实验提取的同位素核温度为 4 7±1 2MeV及S/A =2 5± 0 5 ,根据熵和核温度的关联关系 ,可以确定其Breakup密度接近但小于 0 1(ρ/ ρ0 ) 相似文献
977.
The size of a cylindrical photoacoustic cell with suitable size was selected so that the resonant frequency of the first radial mode was equal to that of a longitudinal higher mode. By maintaining two thin coaxial tubes at each end, a enhanced photoacoustic cell was constructed with two tubes of 1/2 and 1/4 of the wavelength. In this enhanced photoacoustie cell, both the first radial resonance and the higher longitudinal resonance were excited adequately. Coupling of two acoustic modes makes the acoustic energy concentrating in the middle of the cell. The surface loss was decreased, the acoustic quality factor and pressure amplitude increased obviously as compared with conventional cylindrical cell. 相似文献
978.
A tunneling-type magnetoresistance (MR) as large as 158% is observed at T = 300 K in a polycrystalline Zn0.41Fe2.59O4 sample, in which the Zn0.41Fe2.59O4 grains are separated by insulating alpha-Fe2O3 boundaries. The huge room-temperature MR is attributed to the high spin polarization of Zn(0.41)Fe(2.59)O4 grains and antiferromagnetic correlations between magnetic domains on both sides of the insulating alpha-Fe2O3 boundary. The MR exhibits strong temperature dependence below 100 K and its magnitude is enhanced to reach 1280% at 4.2 K, which may arise from the Coulomb blockade effect. 相似文献
979.
980.
Jianpeng Li Dingshu Xiao Peichu Wang Hongyan Chen Minghua Deng Degang Zhu Jie Yu 《Particle & Particle Systems Characterization》2023,40(1):2200141
Transition metal compounds anchored on N-doped carbon (NC) show intrinsic activity and stability for oxygen reduction reaction (ORR). However, the interaction between the transition metal compounds and NC still needs to be strengthened for electron transfer at the compounds/carbon interface. Herein, Fe/Fe3C hybrid nanoparticles encapsulated into N-doped carbon (Fe@NC) are used as high-performance ORR catalysts. Benefiting from the strong interaction at Fe/Fe3C nanoparticles/NC interface, the electrons can transfer from Fe/Fe3C hybrid nanoparticles to NC, redistributing the electron density of active sites and promoting the ORR process. The as-synthesized Fe@NC exhibits outstanding ORR catalytic activity with an onset potential of 1.01 V and a half-wave potential of 0.92 V in alkaline media. It also shows prominent cycling stability and tolerance to methanol crossover, superior to Pt/C catalyst. The theoretical analysis reveals that the Fe nanoparticles have regulated the electron distributions at the heterojunction interface. The Gibbs free energy diagrams for ORR illustrate that the rate-determining step is the conversion of OH* to OH−. In situ Raman spectra give evidence of O-containing intermediates to prove the ORR process. 相似文献